Electrical heating unit



F. KUHN AND J. A. HAND.

ELECTRICAL HEATING UNIT. APPLICATION FILED JAN. I8. 1917.

Patentd June 24, 1919.

dwomup To all whom it may concern:

sT TEs PATENT OFFICE.

KUHN' AND JAY A. HAND, OF bETROIT, MICHIGAN, ASSIGNORS TO AMERICAN ELECTRICAL HEATER COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

nLncrmcAr. HEATING UNIT.

Be it known that we, FRANK KUHN and JAY A. j HAND, both citizens of the United States of 'Aanerica, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Electrical Heating Units, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to electrical heating units of the type in which the resistor is supported in a' refractory; insulator base. One form of unit of this type is that in which the insulator base is rovided with a spiral move in the face t ereof in which the resistor is laid, the depth of the groove being sufficient to prevent contact between the resistor and the utensil to be heated-supported on the base.- There is, however, danger thatthe contents of the utensil may .be spilled upon thebase, thereby short-circuiting the resistor. With our improved construction this danger is avoided by filling the spiral groove above the resistor. with a refractory insulating material and one which is a good conductor of heat.

Another defect of the constructions heretofore used isthe' danger of cracking of the insulator base, due to the greater heat 1mparted to the central portion thereof than" that which iscommunicated to the peripheral portion.v This we have avoided by a series of slits in the peri hery, which permit unequal expansion an contraction without danger of fracture.

In the drawings: Figure 1 is a perspective view'of the unit;

Fig, 2 is a cross-section thereof;

Fig. 3 is a bottom plan view.

A is a disk-shaped insulator base, formed of a suitable refractory material and provided with a spiral groove B in its upper face for receivingthe resistor C. At the p)eriphe1'y of the base is a depending flange and radially extending ribs E on the bottom of the base serve to brace and strengthen the same. F is a lateral extension at one side of the base, on which the terminal contacts G are mounted. In assembling Specification of Letters Patent. Patented June 24,

Application filed January 18, 1917. Serial No. i43,158.

the "unit 'the resistor C is first laid in the spiral groove B and the terminal ends are' connected to the contacts G. The groove B is then filled with a lastic heat-conducting material H, flush wit the upper face of the base. The filling material is preferably a better heat conductor than the material from which the base is formed, and consequently V the heatof the resistor is to a: large extent conducted upward through this material.

At the periphery of the base there are a number of radial slots I, which pass completely through the flange D at a point intermediate the connection of the ribs E thereto. These slots will permit the slight separation of the segments on opposite sides thereof, so that when the center of the base is heated to a'greater degree than the pe-' riphery, there is no danger of fracture. What we claim as our invention is:

1. In an electrical heating unit, the combination with a refractory base havin a grooved upper face, of a'resistor located in said groove, and a filling for said groove of a refractory material having a greater heat conductivity than the body of the base.

2. In an electrical heating unit, a. .base formed of refractory material and provided with a peripheral flange and radial ribs, said peripheral flange-being slitted to divide the same into a number of separate segments, and a resistor embedded in said base.

3. In an electrical heatingunit, the combinationwith a base of refractory material, having a spiral groove in the upper face thereof and provided with a peripheral flange and radial strengthening ribs in the bottom portion, said peripheral flange being slitted at intervals to divide the same into a plurality of separate segments, a resistor arranged in said spiral groove, and a filling in said groove of refractory material having a greater heat conductivity than the body of the base, said filling being flush with the upper face of the base.

4. An electrical heating unit, comprising a refractory base provided with a grooved face having a'plurality of revolutions surrounding each other, and a resistor mounted in said groove, said base having inwardly extending slits in its periphery to divide the In testimony whereof'we aifix our signasame into a number of separate segments. tures in presence of two witnesses. 5. An electrical heating unit, comprising FRANK KUHN, a refractory base and a resistor embedded 1 JAY A. HAND. 5 therein, said base having inwardly extend- Witnesses: v

'ing slits in its periphery to divide the same HARRY W. LUYGKX, into a number of separate parts. 7 ARCHIE OAKES.- 

